From: Clemens Ladisch <clemens@ladisch.de>
To: Takashi Iwai <tiwai@suse.de>, Mark Brown <broonie@kernel.org>
Cc: alsa-devel@alsa-project.org,
Daniel Thompson <daniel.thompson@linaro.org>,
Mark Brown <broonie@linaro.org>
Subject: Re: [PATCH] ALSA: Provide a CLOCK_MONOTONIC_RAW timestamp type
Date: Tue, 08 Jul 2014 19:01:48 +0200 [thread overview]
Message-ID: <53BC23FC.7000108@ladisch.de> (raw)
In-Reply-To: <s5hr41vopyt.wl%tiwai@suse.de>
Takashi Iwai wrote:
> Mark Brown wrote:
>> For applications which need to synchronise with external timebases such
>> as broadcast TV applications the kernel monotonic time is not optimal as
>> it includes adjustments from NTP and so may still include discontinuities
>> due to that. A raw monotonic time which does not include any adjustments
>> is available in the kernel from getrawmonotonic() so provide userspace with
>> a new timestamp type SNDRV_PCM_TSTAMP_TYPE_MONOTONIC_RAW which provides
>> timestamps based on this as an option.
>
> This looks good to me. Or, thinking of the original use case, should
> we just replace ktime_get_ts() with getrawmonotonic()? The MONOTONIC
> mode is really to be monotonic.
This would break any applications that relate these timestamps to their
own timestamps from clock_gettime(CLOCK_MONOTONIC).
Regards,
Clemens
prev parent reply other threads:[~2014-07-08 17:02 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1404831109-8008-1-git-send-email-broonie@kernel.org>
2014-07-08 15:00 ` [PATCH] ALSA: Provide a CLOCK_MONOTONIC_RAW timestamp type Takashi Iwai
2014-07-08 16:00 ` Mark Brown
2014-07-08 19:54 ` Jaroslav Kysela
2014-07-09 11:02 ` Takashi Iwai
2014-07-08 17:01 ` Clemens Ladisch [this message]
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